The present invention relates to a method and apparatus for controlling continuous photography by a camera, and in particular to a camera in which a common motor is used to drive a taking lens for focusing as well as to release a shutter.
In order to make it possible for anyone to enjoy photography at ease, there have been provided such cameras that have an automatic exposure (AE) system, an autofocus (AF) system, an automatic film advancing system, and other functions. For the same reason, these cameras are often formed as inexpensive compact cameras. Thanks to these systems and functions, it is necessary only to direct the camera toward a subject and to depress a release button, whereupon the camera is automatically focused on the subject, makes an exposure at an appropriate exposure value depending on the present subject brightness and, thereafter, advances the film by one frame to position an unexposed frame in place of the exposed frame in an exposure station.
In this type of compact camera, there is usually a motor adapted to drive as many parts as possible so as to reduce the weight and volume of the camera. For example, in a variable focal length camera such as a dual focal length camera or a zoom camera, a first motor is used not only to change the focal length of the taking lens, but also to transport the film. A second motor, a stepping motor for instance, is used to move the taking lens from an initial position into an in-focus position for focusing and, thereafter, to open and close the shutter to make an exposure.
However, a problem arises in the above-described camera using a common motor not only for focusing but also for exposure, when the camera is required to perform continuous photography, that is, when the camera is required to take plural pictures in rapid succession. Namely, in the above-described camera, the stepping motor is actuated upon depression of a release button, thereby at first moving the taking lens along the optical axis from the initial position into an in-focus position, and thereafter driving the shutter blade to open and then close so as to make an exposure. A series of these shutter release operations is terminated after moving the taking lens back to the initial position. Because this sequence is intended to move the taking lens back and forth for each exposure, if a plurality of pictures were taken successively by repeating the sequence, the speed of taking would be slow.
In order to perform continuous photography at a high speed, it would be possible to use individual motors for focusing and for driving the shutter blade, but this solution would be disadvantageous from the standpoint of lightness and compactness of the camera.